One of the unusual assets of the Vitra Design Museum is its ever expanding collection of buildings on site: contributions from Frank Gehry, Nicholas Grimshaw, Tadao Ando, Zaha Hadid, Alvaro Siza, and Jean Prouvé make something like an architectural park. The Boisbuchet site, which is owned and run by the Museum’s director Alexander von Vegesack (who also runs CIRECA) although more modest in scale, has this same experimental quality, and the freedom here has allowed many prototypes and one-offs to be left standing from which future generations of designers can learn or draw inspiration.

The most recent addition to the Domaine, which opened with a traditional tea ceremony in June, is a Japanese Minka guesthouse (kyakuden), relocated to Boisbuchet from the Japanese prefecture of Shimane, where abandonment and dereliction were its likely fate. This is a special case, but aside from this and the original farm buildings, most of the other constructions are the result of summer workshops.

There is a Paper Pavilion by Shigeru Ban, a lattice structure dome by Jörg Schlaich (who developed the Olympic stadium in Munich with Otto Frei), several bamboo buildings by Colombian architect Simón Vélez, a pyramid, a stacked log cabin – as well as various bits of permanent furniture and installations that have never been uninstalled.

The spaces of the old buildings themselves are well suited to the activities of the workshops – old converted barns lend themselves to large scale construction, tool rooms, open sided workshops and storage for copious materials, and to accommodating mealtimes when it’s raining, or just too hot outside. In fact the soothing coolness of the original buildings even in the heat of midday is a lesson in passive environmental design in itself.

This, or rather ‘Learning from the Vernacular’ is the subject of an exhibition currently installed in the partially renovated rooms of the Chateau, displaying dozens of scale models of vernacular forms from all over the world. The Chateau itself is not perhaps an example of that, being a 19th century fantasy concoction that looks oddly like the Walt Disney Castle. But wandering through its labyrinth of aging rooms – the walls patched with remnants of wallpaper from another time, tall windows full of green vistas and lizards sliding through cracks in the floor – is an almost-fairytale experience in itself.

In line with CIRECA’s mission, the whole site will be opened up to the public, who can visit by guided tour, from 1 July 2009. The visitor centre is in the former Mill, the oldest (17th century) surviving structure at Boisbuchet, and there have been preparations all week to prepare the café for potential guests.

However I won’t know if the first day of public access has gone smoothly until later, as tomorrow I’m joining the porcelain group on a visit to the Limoges factory. Knowing almost nothing about the Porcelain process, apart from what I’ve seen so far in the workshop, this will hopefully be an interesting day. More on this tomorrow.

As for what I did today – we started our own lighting projects, and, just to make life difficult for myself, I’m trying to make a sphere. I’ll let you know how I get on… Here’s my ‘prototype’ anyway: